Study On Imaging Of FMCW SAR

The combination of frequency modulated continuous wave (FMCW) technology and synthetic aperture radar (SAR) should pave the way for the development of a small,lightweight, low-cost and high resolution imaging sensors. The highly miniaturized FMCW SAR system satisfies the requirement of cost-effective development trend and it's small enough to be mounted on such Mini Umanned aviation vehicle (MUAV). Therefore FMCW SAR system plays an important role in both military and civilian domains, so more and more research organizations show a great interest in it.Compared with Pulsed SAR, FMCW SAR is different in translating signals, and the fact that the"stop-go-stop"approximation used for the derivation of pulsed SAR is not valid because the FMCW SAR is continuously transmitting signals while platform moving. Therefore they are different in the echo signal model,imaging processing and motion compensation etc.At first this thesis discusses the basic principles of FMCW SAR. It discusses the principles that FMCW SAR improves range resolution in FMCW ranging, and the principles that FMCW SAR improves azimuth resolution. Then it gives the echo model of FMCW SAR system. In succession, it discusses the pulsed SAR Frequency Scaling(FS) algorithm, and based on the echo model of FMCW SAR, the modified FS algorithm is discussed which is suit for FMCW SAR.In study on the motion compensation in FMCW SAR system, a new motion compensation method is proposed which is suit for FMCW SAR system. It is based on the principles of Dechirp. This method of motion compensation considers the range walk and the range cell migration which are introduced by the continuously moving of the platform. This method is different form the conventional pulsed method. It is suitable for the FMCW SAR system.At last, this thesis summarizes the main results of the study and analyses the difficulty and problems which will be faced in the developing of the FMCW SAR system.